1. Field of the Invention
The present invention relates to a thrust plate assembly for a friction clutch in a motor vehicle.
2. Description of the Related Art
Thrust plate assemblies for motor vehicle clutches typically comprise a housing with a pressure plate arranged herein. The pressure plate is connected to the housing via a connection arrangement so that the pressure plate is substantially fixed with respect to rotation relative to the housing and axially displaceable relative to the housing. An energy accumulator such as, for example, a diaphragm spring is arranged to act between the housing and the pressure plate, applying a force to the pressure plate in the direction of the axis of rotation for generating an engaging force.
In a thrust plate assembly of the type mentioned above, the connection arrangement between the pressure plate and the housing generally comprises a plurality of tangential leaf springs, as they are called, which have a first end arranged at the housing and a second end arranged at the pressure plate. These tangential leaf springs provide for the desired holding of the pressure plate with respect to the housing. Further, these tangential leaf springs generate a force which biases or pretensions the pressure plate in a direction opposite to the application of force of the energy accumulator.
In modern automotive construction, different vehicle components are delivered by modules and are not assembled until the final assembly phase. This modular procedure also applies to friction clutches in which thrust plate assemblies such as those described above are initially assembled separately, for example, by the manufacturer and are only subsequently combined with a clutch disk and flywheel to complete the friction clutch. In this regard, a basic problem arises in that the energy accumulators generate a relatively large force which presses the pressure plate out of the housing. This large force would have to be absorbed exclusively by the connection arrangement which can produce unwanted excessive deformation of the connection arrangement, especially when the connection arrangement is constructed from the tangential leaf spring elements described above. Therefore, it is known to provide separate transport safety elements at the pressure plate, for example, by which the pressure plate is attached to the housing so that a direct force return is created between the pressure plate and housing when the application of force by the energy accumulator is not opposed by a counterforce through a clutch disk or the flywheel. However, providing a separate transport safety device of this type requires an additional work step and additional components which are sometimes lost or hidden in the clutch, i.e., are not removed or cannot be removed after the clutch is assembled.
Therefore, it is the object of the present invention to design a thrust plate assembly in such a way that excessive loading of the connection arrangement is avoided without providing additional components.
According to the invention, the object is met by a thrust plate assembly, particularly for a friction clutch in a motor vehicle, comprising a housing, a pressure plate connected to the housing so that it is displaceable in the direction of an axis of rotation and is substantially fixed with respect to rotation relative to the housing. The thrust plate assembly also includes an energy accumulator acting between the housing and the pressure plate for applying a force to the pressure plate in the direction of the axis of rotation for generating an engaging force. A contact arrangement is arranged at the housing and/or the pressure plate so that the energy accumulator contacts this contact arrangement when a predetermined position is reached. The application of force to the pressure plate by the energy accumulator is at least reduced when the energy accumulator contacts the contact arrangement.
The construction of the thrust plate assembly according to the present invention ensures that components which are already provided assume the function of a transport safety device in that the contact of the energy accumulator at the contact arrangement reduces the loading of the pressure plate by the energy accumulator at least to the extent that an unwanted impairment of the connection arrangement is prevented.
For example, the energy accumulator comprises a radial outer supporting area supported at the housing and an application area for applying force to the pressure plate located on the radial inner side of the supporting area. The energy accumulator further comprises a contact area for contacting the contact arrangement located radially inside the application area.
In this embodiment, the contact arrangement is provided at the pressure plate.
In an embodiment of this kind, the thrust plate assembly is preferably constructed such that an application portion is provided at the pressure plate. The energy accumulator is arranged for applying force to the pressure plate via the application portion and the contact portion which the energy accumulator contacts is provided at the pressure plate on a radial inner side of the application portion.
A very simple and reliably acting construction can be achieved in this way when the contact portion comprises a surface region of the pressure plate.
In an alternative embodiment, the energy accumulator may apply force to the pressure plate in a radial outer application area. The energy accumulator is supported at the housing in a supporting area located radially inside the application area, and can contact the contact arrangement in its contact area located radially inside the supporting area.
In this embodiment, the contact arrangement is preferably provided at the housing.
The thrust plate assembly according to the invention may further comprise a supporting portion formed at the housing with the energy accumulator being supported at this supporting portion. A contact portion which the energy accumulator contacts is provided radially inside the supporting portion. In this case, the contact portion preferably comprises a surface region of the housing.
For example, the contact portion at the housing may comprise at least one contact projection.
In modern thrust plate assemblies or friction clutches, a wear compensating adjustment device generally ensures that wear on friction linings of a clutch in the thrust plate assembly which occurs during operation is automatically compensated. However, before the thrust plate assembly is joined with a flywheel and clutch disk to complete the friction clutch, unwanted wear adjustment due to the absence of a supporting force of the pressure plate must be prevented. For this purpose, the present invention further provides that the energy accumulator applies force to the pressure plate via a wear compensating adjustment device which is pretensioned in the wear compensating adjustment direction. Furthermore, a blocking arrangement is associated with the wear compensating adjustment device and prevents wear compensating adjustment in a state in which there is no wear to compensate.
The blocking arrangement may, for example, comprise at least one blocking spring element which opposes the pretensioning of the wear compensating adjustment device in the wear compensating adjustment direction.
As was already mentioned, thrust plate assemblies of the type mentioned above have connection arrangements including a plurality of spring elements, preferably tangential leaf springs, acting between the pressure plate and the housing.
The present invention is further directed to a friction clutch which is outfitted with a thrust plate assembly according to the invention.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.